The invention relates to a cooling water pump, for an internal-combustion engine in particular, with a casing provided with at least one bearing designed to support a pump shaft, with a sealing element devised to seal the bearing against a working space containing the cooling agent as well as with a leakage chamber arranged in the casing and receiving the cooling agent that leaks through the sealing element.
Cooling water pumps in motor vehicles are exposed to relatively critical working conditions. Long rest periods and great variations in temperature are to be overcome and maintenance-free operation over a long period of time is taken for granted. In practice it proved to be almost impossible to achieve a perfectly tight sealing of the pump though, i.e., the oozing of small amounts of the cooling agent must always be taken into account. It is however unwanted to let this quantify of leakage run out of the pump without further ado, since this would produce the impression that there is a flaw.
The former Austrian Patent Application No. 773/99 by the same applicant discloses a cooling water pump provided with a leakage chamber that may be brought out of shape in direction of the axis of the pump shaft and that is located, in fitting position, underneath the pump shaft. The leakage chamber has an opening to the outside which is at least partially closed by a cover, e.g., by a metal foil. Merely a small opening remains open, through which water vapor may escape or through which cooling water leaking through a failing rotating mechanical seal may overflow. Since the leakage chamber must be tight, the cover has to be glued and additionally calked. An additional communicating bore is needed in order to connect the leakage chamber with the space located between the bearing and the rotating mechanical seal. This leakage chamber is accordingly very complicated in construction and its cost is high.
The document DE 28 46 950 B1 describes a coolant pump for liquid-cooled internal combustion engines with a leakage chamber arranged in a casing and receiving a coolant agent. The leakage chamber designed as evaporation room is formed by a bored blind whole which is locked by a plug. It is unfavorable that for the production of the leakage chamber separate manufacturing steps are necessary.
It is the object of the present invention to overcome these deficiencies and to permit, in a cooling water pump of the type mentioned above, the provision of a leakage chamber in the simplest possible way.
According to the invention this object is achieved by designing the leakage chamber in such a way that it may be brought out of shape by a slider which is pulled in an essentially transverse direction and preferably normal to the plane on the axis of the pump shaft. Thanks to the slider which may be pulled in radial or tangential direction relative to the pump shaft, the leakage chamber, which is preferably arranged on the suction side, can be produced in one single operation. The slider is hereby shaped in such a way that it creates the communicating line between the leakage chamber and a connecting space located between the bearing and the rotating mechanical seal.
The opening is preferably arranged at the highest point of the leakage chamberxe2x80x94seen in the fitting position of the cooling water pump, the opening being preferably encompassed by a flange facing. The fitting position of the leakage chamber is hereby essentially directed diagonally upward so that no cooling water can leak through the leakage chamber. The water vapor however is free to pass the opening. In order to reliably prevent spillage when the vehicle is moving, the leakage chamber is designed as high as possible, the opening being preferably located at least partially above the axis of the pump shaft. In order to reliably prevent vapor from accumulating it is advantageous to have the cross section of the leakage chamber widening toward the opening.
In a preferred embodiment of the invention a leakage bore is provided which leads from the leakage chamber to the outside. Said leakage bore protects the bearing against overflowing cooling water in case of a failure of the rotating mechanical seal. The leakage bore is hereby preferably located underneath the center of the bearing so that overflowing cooling water may drain off the leakage chamber through the leakage bore. A particularly easy way of manufacturing is made possible when the leakage bore is arranged parallel to the axis of the pump shaft. Thus, the leakage bore may be shaped in the direction of the opening of the die casting tool for the casing.
The leakage chamber produced according to the invention may be provided for cooling water pumps having the suction chamber of the cooling water pump and the bearing located on the same side as well as for cooling water pumps in which the suction chamber and the bearing are arranged on different sides of the impeller.